The goals of this project are to move forward as rapidly as possible in developing an effective and safe new biological treatment for cocaine abuse and bring this treatment to the point at which clinical trials are appropriate. The approach that will be taken utilizes gene transfer vectors to deliver a mutated version of human plasma butyrylcholinesterase (BChE), which efficiently hydrolyzes cocaine into metabolites that are largely devoid of toxicity and reward potential. A body of evidence from animal studies indicates that such an approach is capable of preventing and reversing cocaine toxicity while also reducing reward stimulus from the self-administered drug and antagonizing drug-primed reinstatement of drug-seeking behavior. The proposed work will be extended to include nonhuman primates and will widen the range and detail of observations relating to the safety of the cocaine hydrolase enzyme when delivered directly as injected protein and when delivered by gene transfer vectors. The nature and magnitude of therapeutic effects will also be examined in more detail than previously, using a range of pharmacokinetic and behavioral models. After further refinement of enzyme coding sequences for vector driven transduction in vivo, attention will also be given to the issue of producing the optimally effective vector in adequate quantities and under rigorously controlled conditions for ultimate use in humans.